Fibrous nonwoven webs are conventionally prepared by extruding a liquid fiber-forming material through a die to form a stream of filaments, processing the filaments during their travel from the extrusion die (e.g., quenching and drawing them), and then intercepting the stream of filaments on a porous collector. The filaments deposit on the collector as a mass of fibers that either takes the form of a handleable web or may be processed to form such a web.
Typically, the collected mass or web is approximately the same width as the width of the die from which filaments were extruded: if a meter-wide web is to be prepared, the die is also generally on the order of a meter wide. Because wide webs are usually desired for the most economic manufacture, wide dies are also generally used.
But wide dies have some disadvantages. For example, dies are generally heated to help process the fiber-forming material through the die; and the wider the die, the more heat that is required. Also, wide dies are more costly to prepare than smaller ones, and can be more difficult to maintain. Also, the width of web to be collected may change depending on the intended use of the web; but accomplishing such changes by changing the width of the die or proportion of the die being utilized can be inconvenient.